Send disabled event from settings windows

Changes:
 - introduced new event 'disabled', sent from settings popup
 - added unit tests for 'disabled' event handling

Bug: T167365
Change-Id: I048b38122b8843199c86fd1ed9ec2ff21767e114

src/reducers/eventLogging.js

@@ -157,11 +157,11 @@ module.exports = function ( state, action ) {
 		!state.interaction &&
 		action.type !== actionTypes.BOOT &&
 		action.type !== actionTypes.LINK_DWELL &&
-		action.type !== actionTypes.EVENT_LOGGED
+		action.type !== actionTypes.EVENT_LOGGED &&
+		action.type !== actionTypes.SETTINGS_CHANGE
 	) {
 		return state;
 	}
-
 	switch ( action.type ) {
 		case actionTypes.BOOT:
 			return nextState( state, {
@@ -188,7 +188,6 @@ module.exports = function ( state, action ) {
 			) {
 				newState.interaction = undefined;
 			}
-
 			return newState;
 
 		case actionTypes.FETCH_COMPLETE:
@@ -285,6 +284,16 @@ module.exports = function ( state, action ) {
 				} )
 			} );
 
+		case actionTypes.SETTINGS_CHANGE:
+			if ( action.wasEnabled && !action.enabled ) {
+				return nextState( state, {
+					event: {
+						action: 'disabled'
+					}
+				} );
+			} else {
+				return state;
+			}
 		default:
 			return state;
 	}

tests/node-qunit/reducers/eventLogging.test.js

@@ -634,6 +634,47 @@ QUnit.test( 'SETTINGS_SHOW should enqueue a "tapped settings cog" event', functi
 	);
 } );
 
+QUnit.test( 'SETTINGS_CHANGE should enqueue disabled event', function ( assert ) {
+	var state = eventLogging( undefined, {
+		type: 'SETTINGS_CHANGE',
+		wasEnabled: false,
+		enabled: false
+	} );
+
+	assert.equal(
+		state.event,
+		undefined,
+		'It shouldn\'t enqueue a "disabled" event when there is no change'
+	);
+
+	state = eventLogging( state, {
+		type: 'SETTINGS_CHANGE',
+		wasEnabled: true,
+		enabled: false
+	} );
+
+	assert.deepEqual(
+		state.event,
+		{
+			action: 'disabled'
+		},
+		'It should enqueue a "disabled" event when the previews has been disabled'
+	);
+
+	delete state.event;
+	state = eventLogging( state, {
+		type: 'SETTINGS_CHANGE',
+		wasEnabled: false,
+		enabled: true
+	} );
+
+	assert.equal(
+		state.event,
+		undefined,
+		'It shouldn\'t enqueue a "disabled" event when page previews has been enabled'
+	);
+} );
+
 QUnit.test( 'ABANDON_END should enqueue an event', function ( assert ) {
 	var dwelledState,
 		token = '0987654321',